PacifiCorp pushing back date to end coal use at Naughton Unit 3 in Wyoming

The Wyoming Department of Environmental Quality’s Division of Air Quality is taking comment until Jan. 16 on its intent to approve a request by PacifiCorp to modify monitoring, recordkeeping, and reporting (MRR) conditions that apply to Unit 3 at the Naughton Power Plant for best available retrofit technology (BART).

PacifiCorp has also requested that the division revise the dates for the end of coal firing and the start of natural gas firing for Unit 3 to align with the requirements of the Wyoming Regional Haze State Implementation Plan (SIP).

In July 2015, PacifiCorp applied to the Division of Air Quality to modify MRR conditions that apply to Unit 3 at the Naughton Power Plant for BART. Per Air Quality Permit MD-14506, Unit 3 at Naughton will cease to burn coal on or before Jan. 1, 2018, and a conversion to natural gas firing will be completed by June 30, 2018. The division has accepted conversion of Unit 3 to natural gas as an alternative to installing and operating controls determined to be BART.

PacifiCorp is requesting the incorporation of MRR requirements from the Federal Implementation Plan (FIP) for regional haze for Wyoming for permits pertaining to BART requirements for Unit 3 at Naughton. The MRR requirements from the regional haze FIP include a condition that permitted emission limits “shall apply at all times, including startups, shutdowns, emergencies, and malfunctions.”

On Oct. 21, 2016, PacifiCorp requested that the division change the dates for the end of coal burning and the start of natural gas firing for Naughton Unit 3. To align the timing of the Naughton Unit 3 gas conversion with the Wyoming Regional Haze SIP, PacifiCorp is requesting that the division modify a permit condition to reflect that PacifiCorp will have, at a minimum, until June 30, 2019, to complete the Naughton Unit 3 gas conversion. In addition, PacifiCorp requested that the division make a change to reflect that the unit will be allowed to continue to operate on coal under the current permit conditions (which have required the unit to operate at a reduced load since April 2015) until Jan. 30, 2019.

The EPA approved Wyoming’s Regional Haze SIP for the Naughton plant in January 2014, and in accordance with that approval, emission controls determined to represent BART for the Naughton plant would be required by Jan. 30, 2019. Because the division has accepted conversion of Unit 3 to natural gas as an alternative to installing and operating controls determined to be BART, the division will utilize this permitting action to require that PacifiCorp complete the Naughton Unit 3 gas conversion by June 30, 2019, and that coal firing for Unit 3 cease by no later than Jan. 30, 2019.

The Naughton Power Plant is located about four miles southwest of Kemmerer in Lincoln County, Wyoming. Naughton is comprised of three pulverized coal units with a total net total capacity of 700 MW. Units 1 and 2 will remain on coal after the Unit 3 conversion. The plant gets much of its coal via conveyor belt from adjacent Westmoreland Coal mining operations.

  • Naughton Unit 1 commenced operation in 1963 and has a maximum heat input of 1,850 million British thermal units per hour (MMBtu/hr). The unit generates a nominal 160 MW.
  • Naughton Unit 2 commenced operation in 1968, has a maximum heat input of 2,400 MMBtu/hr, and generates a nominal 210 MW.
  • Naughton Unit 3 commenced operation in 1971, has a maximum heat input of 3,700 MMBtu/hr, and generates a nominal 330 MW.

The Westmoreland Coal website says about the company’s Westmoreland Kemmerer Inc. (WKI) subsidiary: “WKI was formed to acquire the assets of the Kemmerer Mine from Chevron Mining in 2012. Unlike Westmoreland Coal Company’s other mines that use draglines for mining, Kemmerer is a truck and shovel operation. The Kemmerer Mine is a 13,400-acre mine complex located in the southwest corner of Wyoming. It supplies coal to the Naughton Power Station by overland conveyor and to a number of industrial customers either by rail or truck.”

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.